Let \(R\)  be a ring. From [1]}, Wisbauer introduced the notion of \(\sigma [M]\)  the full subcategory of \(\mathsf {Mod}\hspace{0.72229pt}R\)  formed by the
modules subgenerated by \(M\) . It was shown that a good
homology theory is possible in \(\sigma [M]\) . For example, it is a Grothendieck category with enough injective modules and arbitrary products exists.
